The present disclosure pertains generally to radiant heaters wherein the primary source of heat transferred from the heater to the object being heated is by radiant heat transfer. More particularly, this disclosure pertains to radiant heaters that are designed to heat large areas of buildings with high ceilings. Such areas are typically found in large manufacturing operations, warehouses or logistic areas, hangers for aircraft where maintenance crews may be working, and so forth.
In these types of applications, it is desirable for the heaters to be located at or near the ceiling. Radiant heat, wherein energy is transferred by the emission of light having wavelengths in the infrared to visible regime, transfers energy from the heater unit to surroundings (floors, people, or other objects) by the absorption of these light particles, also called photons, by said surroundings. Unlike the other common modes of heat transfer, convection and conduction, photons travel through air for long distances without substantially heating the air. Convection is a means of transferring energy by heating a fluid, in this case air, followed by the motion of the fluid, and finally the transfer of energy from the heated fluid to a remote object. Conduction is a means of energy transfer whereby the energy flows through a material by electronic vibrations and motions, from a region of higher temperature to a region of lower temperature. Both convection and conduction are inefficient means of transferring energy over large distances, as they require heating the intervening materials.
A primary advantage of radiant heaters is that energy is transferred from the heater to the objects and in close proximity of objects where heat is desired, without having to heat all of the air between the heater and the objects requiring heat. Inevitably, air is heated when it comes in contact with any object that is at a higher temperature than the air. Air that is hotter than the surrounding air will rise towards the top of the air mass. Therefore, the heat transferred from any hot object or heater to the surrounding air will be substantially wasted in a configuration where the heater is near the ceiling of the building to be heated. In fact, only by heating the entire air mass within a building will objects near the floor of the building be heated by contact with the hotter air. Energy that is expended in heating the air near the ceiling of a high-ceilinged structure is substantially wasted with regards to the task of heating people and objects near the floor of the structure.